posted by
martyb
on Sunday July 09 2017, @11:03AM
from the should-start-a-lottery-on-when-it-finally-calves dept.

An Anonymous Coward writes:

As the Larsen C ice shelf moves closer to calving one of the largest icebergs on record, there are clear signs of changes in the part of the shelf which is about to calve. In late June 2017, the soon-to-be iceberg tripled in speed, producing the fastest flow speeds ever recorded on Larsen C, and seemed to be on the verge of breaking free.

The latest data from 6th July reveal that, in a release of built-up stresses, the rift branched several times. Using data from ESA’s Sentinel-1 satellites, we can see that there are multiple rift tips now within 5 km of the ice edge. We expect that these rifts will lead to the formation of several smaller icebergs, as well as the large iceberg which we estimate will have an area of 5,800 sq km. Despite this, the iceberg remains attached to the shelf by a thin band of ice. It is remarkable how the moment of calving is still keeping us waiting.

Related Stories

It's finally adrift. When the Larsen C Ice Shelf calved yesterday [Wednesday], it sent one of the largest icebergs ever recorded slipping into a sea frosted with smaller chunks of ice. It marked the end of a decades-long splintering first seen by satellites in the 1960s. The crack stayed small for years until, in 2014, it began racing across the Antarctic ice.

The massive iceberg holds twice as much water used in the United States every year, according to calculations by Peter Gleick of the Pacific Institute. It weighs about 1.1 trillion tons and measures 2,200 square miles. Its volume is twice that of Lake Erie.

"The iceberg is one of the largest recorded, and its future progress is difficult to predict," said Adrian Luckman of Wales' Swansea University, who led a project tracking the crack since 2015. "It may remain in one piece but is more likely to break into fragments. Some of the ice may remain in the area for decades, while parts of the iceberg may drift north into warmer waters."

By mass, the iceberg accounts for 12 percent of the Larsen C Ice Shelf. It's large enough that maps will have to be redrawn. Larsen C was the fourth-largest ice shelf in the world. Now it's the fifth.

In this particular political moment, the calving of a major iceberg has made headlines around the world. Environmental groups connected the event to climate change and the Trump administration's withdrawal from the Paris climate accords. But scientists have cautioned that the story of the iceberg, which will be known as A68, is more nuanced. Climate signals are not clear enough to attribute the event to rising levels of carbon dioxide, but human activity may have contributed to its calving nonetheless.

The ecosystem in between the Larsen Ice Shelf and a giant iceberg is due to be studied:

Scientists will set out in the next week to study an Antarctic realm that has been hidden for thousands of years.

A British Antarctic Survey-led team will explore the seabed ecosystem exposed when a giant iceberg broke away from the Antarctic Peninsula in 2017.

The organisation has also released the first video of the berg, which covers almost 6,000 sq km.

[...] British Antarctic Survey marine biologist Dr Katrin Linse, who is leading the mission, said that the calving of the iceberg, which has been named A68, provides researchers with "a unique opportunity to study marine life as it responds to a dramatic environmental change". "It's important we get there quickly before the undersea environment changes as sunlight enters the water and new species begin to colonise," she explained, adding that the mission was "very exciting".

A one trillion tonne iceberg – one of the biggest ever recorded - has calved away from the Larsen C Ice Shelf in Antarctica. The calving occurred sometime between Monday 10th July and Wednesday 12th July 2017, when a 5,800 square km section of Larsen C finally broke away. The iceberg, which is likely to be named A68, weighs more than a trillion tonnes. Its volume is twice that of Lake Erie, one of the Great Lakes.

Re:Reminder of climate change(Score: 2) by HiThere on Sunday July 09 2017, @06:05PM

I don't think it's fair to say that they are unrelated to climate change. It *is* fair to say that no direct link can be established to any particular event. But temperature of the ice affects the speed with which the glacier (on land) moves, and so does any subsurface melt...which is affected by the general temperature of the air which is affected by global warming. (Actually by any climate change, but the Arctic and Antarctic regions are warming during the current change.)